Anexperiment to simulate the stresses of a manned mission to Mars on humans couldcost more than $15 million, according to Russian wire reports.

Theestimate comes after a two-week test run using a mock-Mars habitat built at theMoscow Institute of Biomedical Problems for the Russian Academy of Sciences,the country's Interfax News Agency reported Sunday. The habitat servesas the core of Russia's "Mars500"long-durationspaceflight experiment to begin in late 2008 or early 2009.

"Thisincludes the modernization of the existing equipment, remuneration toparticipants in the experiment and other expenditures," Interfaxquoted Viktor Baranov, Mars500 supervisor and first deputy director at theinstitute, as saying. "If there are additional expenditures, the totalcost of the project will grow."

Russia'sMars500 project is expected to seal six people in a series of furnished metaltubes for up to 520 days, the length of time required for a crewed expeditionto Mars and back. The European Space Agency (ESA) is working with Russia on theproject and launched its own search for Mars-minded volunteerslast year.

"Wehave an agreement with the ESA that remuneration paid to Russian and Europeanparticipants should be the same," Baranov told Interfax, adding thatqualified volunteers would be eligible for 50,000 Euros (1.8 million Rubles orUS$73,467) for their time sequestered.

The four-modulemock Mars habitat contains about 1,250 square feet (116 square meters) ofliving space, or about the equivalent of a two-story house.

It is splitinto separate medical and living modules, a descent module for landing on Marsand a storage room, ESA officials have said. The long-duration experiment isexpected to simulate the 40-minute delay in communications between Earth andMars, feature mock explorations of the martian surface and recreate the view ofEarth dwindling away into space as the "spacecraft" heads toward thered planet, they added.

Russian researchers rana 14-day test run in November to seek out any pitfalls with their current design,which allowed project managers to set the new cost estimate, Baranov told Interfax.

Last June, theESA announced a call for 12 volunteers to join its portion of the Mars500project, though eligible applicants must pass psychological and stress tests tobe considered. The applicants would be split into three teams, each with fourpeople, to serve on two, 105-day test runs in the Mars habitat and the final520-day expedition, ESA officials have said.